Air cleaner and silencer assembly



Sept. 29, 1959 w. w. MCMULLEN E AL 2, 0 70 AIR CLEANER AND SILENCER ASSEMBLY Original Filed Dec. 7, 1951 2 Sheets-Sheet 1 ATTORNEYS Sept. 29, 1959 w. w. M MULLEN ETA!- AIR CLEANER AND SILENCER ASSEMBLY Original Filed Dec. 7, 1951 2 Sheets-Sheet 2 //7 m m m m ATTORNEYS United States Patent AIR CLEANER AND SILENCER ASSEMBLY Wesley W. McMullen, Flint, and John D. McMichael, Swartz Creek, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Continuation of application Serial No. 260,382, December 7, 1951. This application August 8, 1957, Serial No. 677,419

22 Claims. (Cl. 183-44) This application is a continuation of application Serial No. 260,382 filed in the names of Wesley W. McMullen and John D. McMichael on December 7, 1951, for Air Cleaner and Silencer Assembly, and now abandoned.

This invention relates to air induction and sound attenuating apparatus for engines and has particular relation to air cleaning and inlet silencing means especially applicable for employment in supplying air to and attenuating sounds from carburetors or other induction means that may be embodied in internal combustion engines for automotive or other uses.

It is proposed to provide an air cleaner and silencer apparatus with an outlet passage large enough to communicate with a plurality of passages in a compound or other multiple barrel carburetor and to restrict the outlet passage on the atmospheric side of the sound attenuating means with which the apparatus is provided. Such restriction of the outlet passage provides acoustical impedance means improving the efiiciency of the silencer to attenuate sounds emanating from the induction system of the engine.

It is also proposed to construct a unitary cleaner, silencer and air supply dome structure consisting of a number of separable units which can be easily assembled and disassembled, particularly after the structure is installed on the engine. The several units and the composite structure employed are designed to be simple, rugged, inexpensive and eflicient to supply clean air to and to silence sounds emanating from the induction passages leading to the engine.

It is also proposed to provide a unitary structure embodying separable air cleaner, silencer and air supply dome elements which will be as compact as possible, particularly with respect to the height of the structure which in present downdraft carburetor V-type engines must be reduced to a minimum.

It is also proposed to provide an air supply dome having an inlet capable of placing acoustical impedance in the path of sound emitted by the engine and of directing the sound that may be emitted by the inlet away from the occupants of a motor vehicle with which the structure may be employed. From the dome inlet to the cleaner silencer outlet the structure is constructed in such a way as to reduce local turbulence to a minimum and to supply to the'engine the greatest possible amount of air.

In the drawings:

Figure 1 illustrates a vertical cross sectional view through an air cleaner, silencer and air supply dome structure embracing the principles of the invention.

Figure 2 is a horizontal sectional view through the air dome structure shown by Figure 1 and illustrating in plan view the upper parts of the cleaner and silencer structure embraced in the structure. Figure 2 is taken substantially in the plane of line 22 of Figure 1, looking in the direction of the arrows thereon.

Figure 3 is a view partly in vertical section and partly in elevation of another form of air supply dome struc- ICC ture applied to the cleaner and silencer unit disclosed by Figures 1 and 2.

Figure 4 is a horizontal sectional view of the air supply dome structure illustrated by Figure 3 and showing therein the upper parts of the air cleaner and silencer unit in plan view. Figure 4 is taken substantially in the plane of line 4-4 on Figure 3.

Referring particularly to Figures 1 and 2, the numeral 10 indicates generally an air cleaner and silencer structure, unit or device which is adapted to be supplied with air by an air supply dome indicated at 11. The cleaner and silencer device 10 comprises an outer annular wall 12 which is secured at 13 to the upper annular edge of an inwardly extending bottom wall indicated at 14. The bottom wall 14 is flanged at 16 around the centrally disposed opening formed therein and is there secured to the lower end of a cylindrical outlet conduit or tube indicated at 17. The conduit 17 which projects upwardly within the bottom wall 14 is secured at the upper extremity thereof to the flanged upper edge of a frusto-conical ring indicated at 18. The lower flanged edge of the ring 18 is likewise secured to the flanged upper edge of an outwardly and downwardly tapering part 20 of a channeled annular wall including the ring 18 and indicated generally at 19. Beyond the outer extremity of the outwardly and downwardly tapering part 20 of the wall 19, the wall 19 turns upwardly to form a cylindrical side wall indicated at 21. The side wall 21 terminates above the upper extremity of the annular side wall 12 and the two are peripherally welded or otherwise secured together as indicated at 22. It will be apparent that the walls 12, 14, 17 and 19 provide a hollow annular casing which is generally indicated by the numeral 23. It will also be apparent that the upper wall 19 of the casing provides an annular channel or filter chamber 24 in the upper part of the casing 23, the bottom wall of the channel 24 being tapered as indicated at 18 and 20, and the outer wall being substantially parallel to the central axis of the structure as is indicated at 21.

The space within the casing 23 is divided by a wall 26 into a relatively small lower resonating chamber indicated at 27 and a larger intermediate resonating chamber indicated at 28. The lower end of the tube or conduit 17 is perforated at 29 to provide openings by which the central part of the tube 17 communicates with the resonating chamber 27. The upper end of the tube 17 is perforated at 31 to provide openings by which the space Within the interior of the tube 17 may communicate with the extreme upper end of the resonating chamber 28.

Removably disposed within the annular chamber 24 formed in the upper wall 19 of the casing 23 is an annular filter element indicated generally at 32. The filter element 32 comprises an outer wall 33, a bottom wall 34 and an inner wall 36. The outer wall 33 is spaced from the wall 21 of the casing 23 to provide an annular inlet 37 to the filter element 32. The bottom wall 34 of the cleaner element 32 also tapers outwardly and downwardly but not to such a great extent as the part 20 of the wall 19 to provide a battle chamber 38 in the space between the two. The baifie chamber 38 provides a continuation of the annular inlet 37 so that the air admitted by the annular inlet 37 may continue to flow into the space below the lower wall 34 of the filter element 32. The lower wall 34 of the filter element 32 is perforated throughout the extent thereof as is indicated at 39 for the purpose of permitting the air admitted to the baffle chamber 38 to flow upwardly through the cleaner element 32. The bottom wall 34 is perforated by cutting out angular segments 41 on all sides except a side which extends radially with respect to the central part of the wall 34. These angular segments are turned outwardly in such a way as to provide air straightening vanes or supports for the outer parts of the filter element 32. The lower edges of the segments 41 are supported upon the lower edge of an outwardly tapering part 42 of an annular bafl'le indicated generally at 43. The baflle 43 has an upwardly and outwardly flanged edge 44 the outer flanged edge of which is adapted to rest upon an annular shoulder 46 which is formed adjacent the lower extremity of the part 21 of the wall 19. The inner extremity of the baflie 43 has a flanged end adapted to project between a bead or shoulder 47 formed at the inner edge of the wall 34 and the outwardly flanged edge 48 of the lower part of the inner wall 36. The baffle 43 therefore is secured between the inner wall 36 and the bottom wall 34 of the filter element 32 to be removed from the channel 24 with the filter element 32. The outer surface of the flange 43 is adapted to seat around a shoulder 49 formed by the lower flanged edge of the wall 18 and upon a gasket 50, when the outer flanged edge of the baffle 43 rests upon the shoulder 46. The bottom of the annular channel 24 up to about the level of the flanged outer edge of the baf- 'flev 43 comprises a sump 45 which may be filled with crankcase or other suitable oil. The baflle 43 may be perforated as is indicated at 51 around the tapering part 42 of the baflle which extends above the level of the oil in the sump 45. The filter element 32 is filled with fibrous filtering or other suitable material indicated at 50 in the region between the walls 33 and 36 and above the lower wall 34.

It will be apparent that air admitted to the cleaner element 32 through the annular passage 37 and the baffle chamber 38 will flow upwardly between the segments 41 through the openings 39 and will be cleaned by the filtering material indicated at 50. During this movement of air, the oil level will be somewhat reduced by the movement of the air above the baffle 43. A large part of the oil above the baffle will be swept upwardly into the filter element 32 where it will be picked up by the filtering material 50 and thereafter returned to the sump 45 through the openings 39.

The upper part of the filter element 32 is closed over the outer wall 33 by an end plate or cover 52, the two being crimped together as indicated at 53. The central part of the cover 52 is depressed downwardly as is indicated at 54. Secured to the inner surface of the cover 52 around the downwardly depressed part 54 is an annular spacer indicated at 56. The spacer 56 is severed adjacent the periphery thereof in such a way as to release vanes 57 which can be bent downwardly to provide support members for the spacer 56 around the periphery thereof. The lower extremities of the vanes 57 are adapted to engage the upper flanged edge of an outwardly flared ring indicated at 61. The lower surface of the flanged edge of the ring 64 is adapted to rest upon the outwardly flanged edge of the inner wall 36 of the filter element 32. The filter material 50 within the filter element 32 is retained in position by a screen indicated at 66, the outerperiphery of which is secured within the crimped edges of the filter element indicated at 32. The inner extremity of the screen 66 is held in position beneath the outwardly flanged edge of the inner wall 36. The flared ring 64 continues downwardly within the upper part of the tube 17 of the casing 23 and is there secured to the upper end of a tube 67 which is spaced within the tube 17 in such manner as to provide an annular passage 68 between the two. The upper end of the annular passage 68 terminates in a small high frequency resonating chamber 69 which is formed between the inner wall 36 of the filter element 32, the flared ring 64 and the casing upper wall section indicated at 18.

It will be apparent that the air cleaned by the filter element 32 will flow outwardly therefrom through the screen 66, inwardly beneath the cover 52, through the space between the vanes 57 and downwardly within the flared ring 64 and the tube 67. The air from the tube 67 is delivered into the lower part of the tube 17 QbQve the openings 29 as is provided for by having the lower end of the tube 67 terminate within the tube 17 and a considerable distance above the openings 29. The lower end of the tube 17 forms the outlet from the cleaner and silencer structure to the carburetor of the engine where the air is mixed with fuel to provide a combustible mixture for operating the engine. The lower wall 14 of the easing 23 is provided with a cylindrical end indicated at 71 which is' adapted to be connected to the inlet to the carburetor or any'adaptor means that may be employed on the inlet side of the carburetor. The tube 17 maybe made of any desired diameter, although in the present instance, the tube is made of a somewhat large diameter so that the cleaner and silencer structure will be adaptable for use in connection with a carburetor having a plurality of induction passages in which combustible mixtures are formed for operating the cylinders of the engine or different groups of cylinders of the engine. The tube 17 serves as an air outlet and acoustical inlet for the air cleaning and sound attenuating means disclosed.

In order to insure the maximum effectiveness of the resonating chambers 27, 23 and 69 forelirninating the noises and sounds originating in the induction passages of the engine, it has been found desirable to provide an additional chamber 72 in the central part, of the outlet passage leading from the cleaner and silencer structure. The chamber 72 is formed by a tube 73 which projects downwardly in spaced relation within the interior of the tube 67 thus providing a relatively narrow annular chamber 74 through which air from the cleaner element 32 may flow to the engine around the tube 73. The tube 73 is secured at the upper end thereof to the inner flanged edge 76 of the spacing member 56. It Will be apparent that certain sound waves travelling from the. engine through the central part of the induction passage formed by the lower end of the tube 17 will be trapped and silenced in the resonating chamber 72. However, the tube 73 will produce an acoustical impedance in the passage 74 on the atmospheric side of the resonating chambers of the silencerand in the lower part of the tube 17 in the vicinity of the openings 29 and adjacent the lower extremity of the annular passage 68 which communicates with the resonating chambers 69 and 23. The impedance to the passage of sound waves from the lower end of the tube 17 will improve the effectiveness of the resonating chambers 27, 28 and 69 which communicate with the induction passage through the openings 29 and 31 and the upper end of the annular passage 68 respectively.

Air for use in the cleaner and silencer structure is supplied to the annular inlet 37 thereto by the dome indicated at 11. The dome 11 is provided with an upper wall 77 adapted to rest upon and be supported by the cover 52 for the cleaner element 32. The central part of the upper wall 77 is depressed at 78 in such a way as to project within the depression 54. formed in the cover 52. The lower wall 79' of the dome 11 is provided with an opening adapted to receive the casing structure 23. The opening referred to is surrounded by a flange 81 on which a resilient gasket 82 is held in place by a ring 33. The inner edge of the gasket 82 is adapted to engage the side wall of the casing 23 in such a way as to form a fluidtight seal therewith. The side wall 84 of the dome 11 is formed by' the laterally bent edges of the walls 77 and 79 which are crimped together at 36 so that the interior of the dome 11 willbe fluid-tight. The dome 11 has an opening 87 formed in. the side wall 84 at one side thereof for the purpose of admitting air to the annular air distribution chamber 88, which is formed within the dome and. around the inlet 37 .to the cleaner silencer unit. It will be apparent from Figure 2 that the side wall 34 is spaced outwardly from the casing 23 to a considerable extent all the way around the inlet 37 but is progressively spaced to a greater extent near the opening 87 in order to insure satisfactory distribution of air to the inlet 37. In the structure disclosed by Figures 1 and 2, the opening 87 receives air from a tube 89, the flared front end of which is indicated at 91. The tube 89 which is of relatively uniform cross sectional area from one end to the other serves as an air inlet and acoustical impedance means for the air cleaning and sound attenuating means disclosed. The end 91 of the tube 89 may terminate above the radiator of an automobile and in such position as to receive air admitted to the front of the radiator and before the air is heated and expanded by passing through and absorbing heat from the radiator. The tube 89 places acoustical impedance in the path of the sound waves emitted from the engine. It will be apparent that the filter element 32 divides the entire space within the casing 23 and the dome 11 into inlet chamber means and outlet chamber means and that all of the space within the two casings comprises acoustical expansion chamber means that serves as acoustical impedance for sounds emitted by the engine.

The dome 11 and the units 32 and 23 are removably secured together by a threaded rod 92, the lower end of which is secured to the carburetor of the engine. The upper end of the rod projects through aligned openings formed in the depressed parts 54 and 78 of the cover 52 in the upper wall 77 respectively. A Wing nut 96 is removably secured upon the upper threaded end of the rod 92 for removably securing the various parts of the assembly together and for securing the assembly in operative relation to the carburetor of the engine.

The cleaner silencer dome structure can be assembled and disassembled with great ease and Within a short time. To disassemble the apparatus it is necessary only to remove the wing nut 96, then to slide the dome 11 off the top of the cleaner silencer structure and then remove the filter element 32 with the cover 52, the spacer 56, the tube 73, the tube 67, the flared ring 64 and the baflle 43 being removed therewith as a unit. The filter element can be cleaned, the oil sump 45 cleaned and refilled and the device reassembled by reversing the operations previously performed in assembling the device.

In the structure described by Figures 3 and 4 the cleaner and silencer structure 110 is the same as the cleaner and silencer structure illustrated by the numeral 10 in Figures 1 and 2. The unit 110 has an annular inlet 137 to which air is supplied for operating the engine by the dome 111. The dome 111 comprises an upper wall 177, a lower wall 179, a side wall 184 and an air scoop 185. The upper wall 177 and the lower wall 179 are flanged inwardly at 197 and 198 respectively for the purpose of providing inwardly disposed annular shoulders adapted to support the opposite edges of the side wall 184. In Figures 3 and 4 the side wall 184 is formed by a separate strip of material of elongated formation which can be bent in such a way as to fit the shoulders formed by the flanges 197 and 198. The ends of the strip forming the side wall 184 terminate in spaced relation to one another in such a way as to provide an opening 199 for admitting air to the annular space 188 between the dome 111 and the cleaner silencer structure 110 for supplying the annular air inlet indicated at 137. The bottom wall 179 is cut out in such a way as to provide a somewhat eccentric space or passage 188 so that the widest part of the space between the side wall and the annular air inlet 137 will be directly opposite the opening 199. The opening in the bottom wall 179 for receiving the cleaner silencer unit 110 is provided with a resilient annular gasket 201 which is supported between a flange 202 formed on the edge of the wall 179 about the opening therein and a flange ring 203 which is centered within a cylindrical part of the flange 202. The gasket 201 projects inwardly beyond the edge of the flange 202 and ring 203 for the purpose of engaging the side wall of the cleaner silencer unit 110 for providing a fluid-tight seal between the dome 111 and the cleaner silencer unit 110. The part of the side wall 184 which surrounds approximately the front half of the cleaner silencer unit 110 is curved in formation as is indicated at 204. The convex surface of the part 204 of the wall 184 is adapted to be positioned in such a way as to face the air stream resulting from the movement of the engine with which the device is employed and the air stream resulting from the cooling fan with which the engine may be provided. This air stream will build up a region of high pressure on the curved part 204 of the wall 184 which will result in increasing the velocity of the air stream on each side of the wall 184 and adjacent the ends of the curved part 204. In order to utilize this high pressure region in the air stream and the high velocity flow of air resulting therefrom, the dome 111 is formed in such a way as to provide the air scoop 185 which extends from just in front of the opposite ends of the part 204 of the side wall 184 and around the back of the dome structure 111. The scoop 185 is formed by deforming parts of the upper Wall 111 and the lower wall 79 inwardly beyond the flanges 197 and 198 respectively, thereby forming an elongated passage 206 around the rearwardly disposed part of the side wall 184. The passage 206 is so positioned that the middle of the passage will discharge through the opening 199 into the space 188 surrounding the annular inlet 137.

It will be apparent that the ram effect of the air stream upon the curved part 204 of the wall 184 may somewhat increase the supply of air available for admission to the inlet 137 by admitting to the opposite ends of the passage 206 the high velocity streams of air which are formed beyond the ends of the part 204 of the side wall 184. These high velocity streams of air will be directed by the air scoop 185 toward the middle of the passage 206 and inwardly through the opening 199 to the space surround ing the annular inlet 137.

However, the principal purpose for the dome 111 and the air scoop 185 is to silence the sound emitted from the engine by placing an acoustical impedance in the path of the sound emitted from the engine through the upper part of the cleaner silencer structure and the cleaner inlet 137. It will be noted that the wall 184 entirely surrounds the inlet 137 except in the vicinity of the opening 199 and that the opening 199 is opposite the middle portion of the air scoop 185. Also it will be noted that the inlets to the passage 206 are directed oppositely from the opening 199 and open in a direction away from the occupants of the vehicle with which the structure may be employed. The passage 206 forms a pair of inlet passage or tube means of relative uniform cross sectional area from one end to the other and places accoustical impedance means in the path of the sound waves emitted from the engine.

The dome 111 may be removed from the cleaner and silencer structure by removing the wing nut 296 from the end of the threaded rod 292 by which the various elements of the air supply dome and a cleaner and silencer unit are secured together, as has been explained in the description of the structure disclosed by Figures l and 2.

We claim:

1. An air induction device for engines comprising a casing forming an annular chamber, an inner wall forming an outlet conduit leading through said casing and adapted to be connected to the carburetor of an engine for supplying air to the carburetor for operating the engine, said casing having an upper wall forming an annular channel, a filter element adapted to project into said annular channel with the outer wall of said filter element being spaced from the outer part of said upper wall of said casing forming said channel to provide an annular inlet for admitting air to the lower part of said filter element, an end cover for said filter element secured to the upper edge of the outer wall of said filter element, a tube having a flanged end engaging the upper end of the inner wall of said filter element and projecting downwardly within said outlet conduit in spaced and concentric relation thereto, the upper end of said tube, the inner wall of said filter element and the inner part of the upper Wall of said casing forming a resonating chamber around the inner wall of said filter element and communicating with said casing outlet through the annular space between said tube and said conduit, said conduit being formed to provide a plurality of openings through the inner wall of said casing and providing communication means between the chamber in said casing and said outlet.

2. An air induction device for engines comprising a casing having an annular inlet type air cleaner formed in the upper part thereof, said cleaner being formed to provide an annular filter element having an inner wall, a pair of annular resonating chambers formed in said casing, one of said resonating chambers being formed below said cleaner, the other radially inwardly with respect to said filter element, a pair of spaced and concentric tubes forming the outlet to said cleaner, the annular space between said tubes being in open communication at the upper end thereof with said resonating chamber within said filter element, and radially disposed passages formed in the outer of said tubes and communicating with th other of said resonating chambers below said cleaner.

3. An air induction device for engines comprising a casing having an annular inlet air cleaner formed in the upper part thereof and a plurality of annular resonating chambers formed therein, a pair of spaced and concentric tubes forming an outlet from said casing, the inner of said tubes being connected to said cleaner for delivering air from said cleaner to said engine, a plurality of openings formed in the outer one of said tubes and connecting the outlet from said casing to one of said resonating chambers beyond the end of the inner one of said tubes, a plurality of openings formed in said outer one of said tubes and connecting another of said resonating chambers to the annular space between said tubes, said chamber being formed to provide a communication between another of said resonating chambers and the end of said annular space remote from said outlet, and a tube spaced within said pair of tubes and having a closed end remote from said outlet for providing a restricted air and sound passage between the silencer outlet and the atmosphere.

4. An air induction apparatus for engines comprising a pair of hollow annular shells, one of said shells providing a resonating chamber shell and the other a filter element chamber shell for said apparatus, the outer and inner walls of said resonating chamber shell being cylindrical in formation, the upper wall of said resonating chamber shell being formed to extend across the space between said cylindrical walls from the upper extremity of said inner wall to a part of said outer wall between the upper and lower extremities thereof, said upper wall and the upper part of said outer wall forming an annular chamber at the upper end of said resonating chamber shell, said filter element shell being disposed within said annular chamber, said filter element shell having an inner wall of greater diameter than the inner wall of said resonating chamber shell and an outer wall of lesser diameter than the outer wall of said resonating chamber shell, a tube having an upper outwardly flanged end disposed in spaced relation to and within the inner wall of said resonating chamber shell to provide an elongated annular passage, the upper flanged end of said tube being secured to the upper edge of the inner wall of said filter element chamber shell to provide a second resonating chamber disposed radially inwardly of said filter element shell and communicating with the outlet end of said inner wall of said resonating chamber shell through said annular passage, a cover for said filter element shell secured to the upper edge of the outer wall of said filter element shell and providing an outlet from said filter element through said outwardly flanged tube and the inner Wall of said resonating chamber shell, and a second tube disposed within and in spaced relation to said first mentioned tube and having the upper end thereof closed by said filter element shell cover.

5. An air induction. apparatus for engines comprising a silencer element, a filter element and a dome, said filter element being projected within a chamber formed in an upper wall of said silencer element and being adapted to be supported by said upper wall and in spaced relation to said upper wall to provide an annular inlet passage for the admisison of air to the lower extremity of said filter element, said air being adapted to be discharged from the upper extremity of said filter element and through an outlet extending through the central part of said upper'wall and said silencer element, a closure for the upper end of said filter element for directing air from said filter element into said outlet in the central part of said silencer element, said dome being provided with an upper Wall and with an opening in the lower wall thereof to permit said dome to telescope upon the upper end of said filter element and said silencer element and to enclose said inlet passage to said filter element, inlet means for admitting air to said dome, and means for clamping said filter element and said filter element closure between said upper wall of said silencer element and said upper wall of said dome;

6. An air" induction device for engines comprising an annular filter element having an end closure member secured over the upper end thereof, an outlet tube of smaller diameter than the inner wall of said filter element and extending downwardly therethrough to provide an outlet from the upper part of said filter element, said outlet tube being connected to the upper edge of the inner wall of said filter element and providing within said filter element a resonating chamber for said induction system, a second tube secured to the central part of said cover and projecting downwardly within said first tube and in spaced relation thereto to provide an annular passage between said tubes forming the outlet from said filter element and a centrally disposed cylindrical resonating chamber, means for admitting air to the lower part of said filter element to be cleaned by said filter element and to pass outwardly to the engine through said annular passage, and a third tube spaced around the outer one of said two first mentioned tubes and providing an annular space communicating with said first mentioned resonating chamber and extending beyond said annular passage to provide an outlet for said induction device.

7. An air induction apparatus for engines comprising a dome having spaced end walls and inner and outer side walls extending between said end walls, one of said end walls having an opening therein adapted to receive an air cleaner in spaced relation to and within said inner wall, said dome being formed and spaced with respect to said opening to provide an inlet chamber between said inner wall and said cleaner in open communication with the inlet for said cleaner, said dome also being formed to provide'an inlet passage between said inner wall and said outer wall and extending around said inlet chamber within said outer wall, said outer wall being formed to provide an inlet on one side of said dome, said inner wall being formed to provide an inlet on the side of said dome opposite said outer wall inlet, said inlet formed in said outer wall being formed to provide inlet openings leading to the opposite ends of said inlet passage, said inner wall between said inlet openings and said inner wall inlet being formed to provide a fluid tight means separating said inlet passage from said inlet chamber except through said inner wall inlet intermediate the ends of said inlet passage.

8. An air induction apparatus as defined by claim 7 and in which said inlet chamber adapted to be formed in the space between said cleaner and said inner wall has the greatest width adjacent said inner wall inlet and decreases in width in opposite directions around said cleaner and has the least width on the side of said cleaner opposite said inner wall inlet.

9. An air induction apparatus for engines as defined by claim 7 and in which said inner wall between said inlet openings is an outwardly curved wall positioned to project into said inlet openings the air which may be incident upon said curved wall during the operation of an engine with which said apparatus may be employed.

be formed in the space between said cleaner and said I inner wall has the greatest width adjacent the inner wall inlet and decreases in width in opposite directions around said cleaner and has the least width on the side of said cleaner opposite said inner Wall inlet, and in which said inner wall between said inlet openings is an outwardly curved wall positioned to project into said inlet openings the air which may be incident upon said curved wall during the operation of an engine with which said apparatus may be employed.

11. An air induction apparatus for engines comprising a dome having spaced end walls and a side wall extending between said end walls, one of said end walls being relatively imperforate and the other having an opening therein adapted to receive an air cleaner having an inlet, said air cleaner being received beyond said opening in spaced relation to and within said side wall, said dome when disposed on said air cleaner providing an inlet chamber between said side wall and said cleaner and in open communication With the inlet for said cleaner, said dome also being formed to provide an inlet opening in said side wall for admitting air to said inlet chamber, said inlet chamber being of greater width adjacent said inlet opening than on the side of said dome opposite said inlet opening and progressively decreasing in width between the parts of said chamber of greater and lesser width.

12. An air induction apparatus for engines comprising a dome having spaced end walls and a side wall extending between said end walls, one of said end walls being relatively imperforate and the other having an opening therein adapted to receive an air cleaner having an inlet, said air cleaner being received beyond said opening in spaced relation to and within said side wall, said dome when disposed on said air cleaner providing an inlet chamber between said side wall and said cleaner and in open communication with the inlet for said cleaner, said dome also being formed to provide an inlet passage extending through said side wall and leading to said inlet chamber, sealing means extending around said opening in said other end wall and adapted to engage the side wall of said cleaner when said cleaner is projected into said opening and to form a relatively fluid tight seal between said cleaner and said dome, and means for removably securing said dome upon said cleaner when said cleaner is inserted through said opening.

13. An air induction apparatus for engines as defined by claim 12 and in which the width of said inlet chamber is greater adjacent said inlet passage and progressively decreases in opposite directions around said cleaner and toward the opposite side of said cleaner.

14. An air intake device for engines comprising an inlet casing having an annular filter element therein and forming an annular filter chamber receiving said filter element and an annular distribution chamber surround ing said filter chamber and said filter element, an annular wall forming a part of said inlet casing and separating said filter chamber and said distribution chamber and providing an annular inlet forming a continuous communication between said distribution chamber and said filter chamber and extending entirely around said filter chamber, said inlet casing also being formed to provide elongated and restricted air supply passage means leading from the atmosphere to said chambers, said air supply passage means being of relatively uniform cross sectional area throughout the length thereof and providing acoustical impedance between said chambers and the atmosphere, said chambers and said air supply passage means being formed to attenuate sounds emanating from said engine through said intake device.

15. An air intake device for engines as defined by claim 14 and in which said air supply passage means is formed to provide a plurality of elongated branch passages of relatively uniform cross sectional area throughout the length of said air supply passage means, said branch passages being connected in parallel between said distribution chamber and the atmosphere.

16. An air intake device for engines as defined by claim 14 and in which said air supply passage means is formed to provide a plurality of elongated branch passages of relatively uniform cross sectional area throughout the length of said air supply passage means, said branch passages being connected in parallel between said distribution chamber and the atmosphere, the ends of said branch passages being positioned to extend in parallel relation at the sides of said distribution chamber and opening in one direction.

17. An air cleaner silencer assembly for internal combustion engines and the like and comprising a casing having an air outlet and acoustical inlet in one wall thereof, said casing being formed internally thereof to provide acoustical expansion chamber means therein, annular filter means in said casing and dividing said chamber means into' inlet chamber means and outlet chamber means, and air inlet and acoustical impedance passage formed in a side of said casing and leading to said inlet chamber means, said air inlet and acoustical irnpedance passage and said acoustical expansion chamber means being formed to attenuate sounds emanating from said engine, said air inlet and acoustical impedance passage directing sounds escaping said sound attenuating means from said side and away from the opposite side of said casing.

18. An air induction and silencer apparatus for engines comprising, a dome having a relatively imperforate end Wall and a side wall and being formed opposite said end wall to provide an opening adapted to receive an air cleaner having an air inlet and acoustical outlet, said air cleaner being received beyond said opening in spaced relation to and within said side wall, said dome when disposed on said air cleaner providing an air inlet and acoustical outlet chamber between said side wall and the air inlet and acoustical outlet for said cleaner, said dome also having a passage in said side wall providing an air inlet and acoustical outlet communicating with said air inlet and acoustical outlet chamber, said passage being restricted in cross section relative to said air inlet and acoustical outlet chamber and providing acoustical impedance in said air inlet and acoustical outlet for said dome, said cross section of said passage throughout the length of said passage and at the atmosphere end of said passage being substantially no greater than at the end of said passage providing said communication with said air inlet and acoustical outlet chamber, said acoustical impedance of said passage and the relation between said passage and said chamber and said cleaner attenuating sounds emanating from said engine.

19. An air cleaner silencer assembly for internal combustion engines and the like and comprising a casing having an air outlet and acoustical inlet in one Wall thereof, said casing being formed internally to provide air distribution and acoustical expansion chamber means, annular filter means in said casing and dividing said chamber means into an air inlet and acoustical outlet chamber and an air outlet and acoustical inlet chamber, said air outlet and acoustical inlet chamber communicating with said air outlet and acoustical inlet in said wall, and an air inlet and acoustical outlet formed in said casing and communicating with said air inlet and acoustical outlet chamber, said air inlet and acoustical outlet being an elongated passage of restricted cross section at said communication with said air inlet and acoustical outlet chamber and providing acoustical impedance in said air inlet and acoustical outlet for said casing, said cross section of said passage throughout the length of said passage and at the atmosphere end of said passage being substantially no greater than at the end of said passage providing said communication with said air inlet and acoustical outlet chamber, said acoustical impedance of said passage and the relation between said passage and said chamber means attenuating sounds emanating. from said engine.

20. An air cleaner silencer assembly for internal combustion engines and the like and comprising a casing having an air outlet and acoustical inlet in one wall thereof, said casing being formed internally to provide air distribution and acoustical expansion chamber means, annular filter means in said casing and dividing said chamber means into an air inlet and acoustical outlet chamber and an air outlet and acoustical inlet chamber communicating with said air outlet and acoustical inlet in said wall, and an air inlet and acoustical outlet formed in said casing and communicating with said air inlet and acoustical outlet chamber, said air inlet and acoustical outlet being an elongated passage of restricted cross section and providing acoustical impedance in said air inlet and acoustical outlet for said casing, said air inlet and acoustical outlet chamber and said air inlet and acoustical outlet passage providing air inlet and acoustical outlet means substan- -tially no greater in cross section at the atmosphere than at the filter end of said air inlet and acoustical outlet means, said acoustical impedance of said passage and the relation between said passage and said chamber means providing means attenuating sounds emanating from said engine.

21. An air cleaner silencer assembly for internal combustion engines and the like and comprising a casing having an air outlet and acoustical inlet in one wall thereof, said casing being formed internally to provide air distribution and acoustical expansion chamber means, annular filter means in said casing and dividing said chamber means into an air inlet and acoustical outlet chamber and an air outlet and acoustical inlet chamber communicating with said air outlet and acoustical inlet in said wall, and an air inlet and acoustical outlet formed in said casing and communicating with said air inlet and acoustical outlet chamber, said air inlet and acoustical outlet being an elongated passage of restricted cross section and providing acoustical impedance in said air inlet and acoustical outlet for said casing, said air inlet and acoustical outlet chamber and said air inlet and acoustical outlet passage providing air inlet and acoustical outlet means. varying in cross sectional area between said an- I2 nul'ar' filter means and the atmosphere, said cross sectional area of said air inlet and acoustical outlet means being less adjacent the atmosphere end than. toward said annular filter means end of said air inlet and acoustical outlet means, said acoustical impedance of said passage and the relation between said passage and said chamber means providing means attenuating sounds emanating from said engine.

22. An air cleaner silencer assembly for internal combustion engines and the like and comprising a casing having an air outlet and acoustical inlet in one wall thereof, said casing being formed internally to provide air distribution and acoustical expansion chamber means, annular filter means in said casing and dividing said chamber means into an air inlet and acoustical outlet chamber and an air outlet and acoustical inlet chamber, said air outlet and acoustical inlet chamber communicating with said air outlet and acoustical inlet in said wall, and an air inlet and acoustical outlet formed in said casing and communicating with'said air inlet and acoustical outlet chamber, said air inlet and acoustical outlet being an elongated passage of restricted cross section and providing acoustical impedance in said air inlet and acoustical outlet for said casing, said air inlet and acoustical outlet chamber and said air inlet and acoustical outlet passage providing air inlet and acoustical outlet means varying in cross sectional area between said annular filter means and the atmosphere, said cross sectional area of said air inlet and acoustical outlet means being less adjacent the atmosphere end than toward said annular filter means end and increasing from adjacent said atmosphere endtoward said annular filter means end of said air inlet and acoustical outlet means, said acoustical impedance of said passage and the relation between said passage and said chamber means providing means attenuating sounds emanating from said engine.

References Cited in the file of this patent UNITED STATES PATENTS 2,114,783 Kowitt Apr. 19, 1938 2,221,717 Nickolson Nov. 12, 1940 2,764,142 McMullen Sept. 25, 1956 2,822,885 Sebok et al. Feb. 11, 1958 

